1. Field of the Invention
The present invention relates to a roller head opening and closing apparatus in a roller head extruder for extruding and pressing materials to be kneaded and mixed such as rubber and plastics.
22. Background of the Related Art
In a roller head extruder, for checking whether there remains rubber or plastics (hereinafter referred to as "residue"), cleaning the residue if any, and for maintenance and inspection of the extruder prior to change of the material in the interior of the extruder, it is necessary to form a maintenance space for at least the upper half of the worker's body between the outlet side of the extruder and a roller head (hereinafter referred to as a "head") which comprises frames, upper and lower rollers and power transmission means. In order to obtain such a space there has been proposed a roller head opening and closing apparatus in a roller head extruder wherein both the head and lower roller driving means ar retracted to the side opposite to the extruder. As an example, such a conventional roller head opening and closing apparatus will be explained below with reference to FIGS. 6 and 7.
In the conventional roller head extruder, a head 67 is provided on the extrudate outlet side of the extruder 51. The head 67 is composed of an upper roller 52 whose lower portion presses the upper surface of the extrudate and which is supported. A lower roller 53 is disposed below the upper roller 52, the lower roller 53 pressing at the upper portion thereof the lower surface of the extrudate and being supported. A pair of support frames 54 are erected to support the upper and lower rollers 52, 53 at both end portions of the rollers. Gears 56 mounted on shaft ends of the upper and lower rollers 52, 53 projecting to the exterior of the frames 54, the gears 56 being in mesh with each other. A cotter 57 is provided for locking and unlocking the frames 54 with respect to the outlet side of the extruder in a position wherein the longitudinal axes of the upper and lower rollers 52, 53 are vertically parallel to each other. An actuator is provided at 65. On the side of the roller 53 opposite to the side where the gear 56 is mounted there is disposed a drive unit 55 connected to the roller 53 through a rotary joint 59, the drive unit 55 comprising an electric motor for rotating the lower roller 53 and a reduction gear. The head 67 and the drive unit 55 are placed on the same movable bed 68, and for retracting the movable bed 68 to the side opposite to the extruder 51 there is provided an actuator 58, one end of which is pivotally connected to the movable bed. Further, below the movable bed 68 there are disposed a plurality of rails 69 which slidably support the movable bed 68.
In the roller head opening and closing apparatus of the above roller head extruder, after the material to be kneaded and mixed is extruded from the extruder 51 and pressed by the upper and lower rollers 52, 53 into a semi-finished product, if there occurs the necessity of changing the material to be kneaded and mixed and if at this time the material before the change remains in the interior of the extruder 51, the quality of the semi-finished product after the material change will be inferior, with a different material incorporated therein. In order to prevent the formation of such an inferior product it is necessary to check the interior of the extruder 51 and clean it if necessary to remove residual rubber or plastics (hereinafter referred to as "residue") before the change of the material to be extruded and pressed. To this end, the actuator 65 is operated to move the cotter 57 upwards to unlock the head 67 from the outlet side of the extruder 51, then the movable bed 68 is allowed to slide on the rails 69 by the operation of the actuator 58 and thereby be retracted to the side opposite to the extruder 51, whereby between the outlet side of the extruder 51 and the head 67 there is formed a space which permits a worker to enter for checking and cleaning the interior of the extruder 51. After the worker checks whether the residue is present in the interior of the extruder 51 and cleans out the residue if any, the movable bed 68 is moved to the outlet side of the extruder 51 by reverse operation of the actuator 58. Then, the cotter 57 is brought down by the actuator 65 whereby the head 67 is locked to the outlet side of the extruder 51. The roller head extruder is now ready to restart the operation of extrusion and pressing after the material change.
In the roller head opening and closing apparatus in the roller head extruder described above with reference to FIGS. 6 and 7, a space which permits a worker to enter is formed between the head 67 and the outlet side of the extruder 51 by retracting the movable bed 68 with the head 67 and the drive unit 55 mounted thereon to the side opposite to the extruder 51. Therefore, a dead space is needed which is not utilized at all during the operation of extrusion and pressing, and it is necessary provide components which are essential but low in degree of utilization, such aS the movable bed 68 and the rails 69.
Further, the electric wiring for supplying electric power to the drive unit 55 must be provided flexibly or in such a manner as to permit a sliding power supply. If the electric wiring is made flexible, it is bent every time the movable bed 68 is retracted, so that the electric wiring may be broken by a strain hardening phenomenon induced by repeated bending, or even if it is not broken, the coating thereof may come into repeated contact with another object, resulting in wear or short-circuiting of the coating. Thus, the reliability thereof is low.
Also, if the electric wiring is constructed for sliding power supply, the maintenance period is required to become shorter due to wear.